Deutsche bank AG is currently undergoing an investigation into the potential money laundering by Russian Clients that may involve about $6 billion worth of transactions over the duration of more than four years.

The Bank of Russia approached Deutsche Bank in October asking the firm to look into the trading activity of some clients in the country.

Deutsche bank is said to be analysing data from 2011 through to early 2015, and has alerted Britain’s financial conduct authority, the European Central Bank and Germany’s Bafin of the investigation.